What is a calorie

There are many common measurement units in life, and different measurement units are also different, so when choosing measurement units, you cannot do it casually. However, it should be noted that you must have a good understanding of the measurement, so that it will be more convenient to use. Calories are very common, but what are calories? Many people are not very clear about it.

When losing weight, we often talk about calories. When choosing foods, we need to know how many calories there are. Each food has a different number of calories. So what is a calorie? It is a unit of energy, and it is easy to understand.

What is a Calorie?

Calorie is a unit of energy. We tend to associate calories with food, but they actually apply to anything that contains energy. For example, 4 liters of gasoline contains about 31 million calories of energy. With the calories in 217 Big Macs, you could drive 22 miles.

Specifically, one calorie of energy or heat raises the temperature of one gram of water by one degree Celsius. 1 calorie is equal to 4.184 joules (joule is a commonly used unit of energy in physics).

Most of us associate calories with something we eat or drink, as in, "This can of soda has 200 calories." In fact, the calories listed on food packaging are kilocalories, also written as capital C, which is equivalent to the heat required to raise the temperature of 1000 grams of water from 14.5°C to 15.5°C at 1 atmosphere of pressure, which is approximately equal to 4186 joules of internal energy. (1000 calories = 1 kcal). So, in reality, that can of soda contains 200,000 calories (but don't worry, this also applies to exercise - when the exercise chart says you burn 100 calories by jogging 2 kilometers, it means 100,000 calories). In English, "calorie" (with a lowercase first letter) means calorie, which is approximately equal to 4.186 joules, and "Calorie" (with a capital first letter) means kcal, which is approximately equal to 4186 joules.

Since scientists later discovered that the specific heat capacity of water is different at different temperatures, the following different definitions were derived:

"15-degree calories" used in nutrition: the heat required to raise the temperature of 1 gram of water from 14.5°C to 15.5°C under 1 atmosphere of pressure is approximately equal to 4.1855 joules. "4 degree calorie": the heat required to raise the temperature of 1 gram of water from 3.5℃ to 4.5℃ at 1 atmosphere of pressure.

"Average Calories" refers to the average number of calories per degree required to raise the temperature of 1 gram of water from 0°C to 100°C at 1 atmosphere of pressure, which is approximately equal to 4.190 joules.

The calories in the International Steam Table are approximately 4.1868 joules.

Thermodynamics and chemistry use the term "thermochemical calorie", which is approximately 4.184 joules.

There are two types of calories:

Kilocalorie, also written as capital C, is most commonly seen on food labels. It is equivalent to the amount of heat required to raise the temperature of 1000 grams of water from 14.5°C to 15.5°C at 1 atmosphere of pressure, which is approximately equal to 4186 joules of internal energy.

Calories, also called cal, are more common in scientific research documents. 1000 Calories = 1 Calorie

Through the above introduction, we have a good understanding of what calories are. This energy unit is very helpful in calculating food energy. However, it should be noted that when using such a unit, it cannot be done arbitrarily, otherwise it will not have any benefits.